Abstract: The degradation of ecological environment in the agriculture-pasture ecotone in northern China has been paid more attentions.Based on our many years' research and under the guide of energy and material flow theory,this paper put forward an ecological management model,with a hill as the basic cell and according to the natural,social and economic characters of Houshan dryland farming area inside the north agriculture-pasture ecotone.The input and output of three models,i.e.,the traditional along-slope-tillage model,the artificial grassland model and the ecological management model,were observed and recorded in detail in 1999.Energy and material flow analysis based on field test showed that compared with traditional model,ecological management model could increase solar use efficiency by 8.3%,energy output by 8.7%,energy conversion efficiency by 19.4%,N output by 26.5%,N conversion efficiency by 57.1%,P output by 12.1%,P conversion efficiency by 45.0%,and water use efficiency by 17.7%.Among the models,artificial grassland model had the lowest solar use efficiency,energy output and energy conversion efficiency;while the ecological management model had the most outputs and benefits,was the best model with high economic effect,and increased economic benefits by 16.1%,compared with the traditional model.

Key words: Energy and material flow, Agriculture-pasture ecotone, Ecological management, Model